The present invention relates to the field of drilling technologies, and to a system for handling equipments for the drilling of the ground.
It is known that the procedures for realizing a digging of the foundation, for consolidation or for drainage of the ground refer with an absolute priority to a tower machine comprising a power assembly and means for drilling and means for digging the ground; said tower being delimited in its upper part by a head and in its lower part by a foot and the power assembly (hydraulic or electric) moves along the over-said tower between the head and the foot, by transmitting the rotary motion and an advancement or lift force to the digging means.
During the course of time, the increasing of power in internal combustion engines and in electric engines have promoted the increase of the drilling diameters, with the need of providing handling systems whose sizes and hardness could be well proportioned, in terms of performances, to the new realizable digging diameters.
The handling system to which can be referred in order to guarantee a constant pushing on the digging tool and/or to remove the battery when the digging is finished, are practically of two kinds:
handling systems with flexible elements: a rope winch or chain motor-reducer;
rigid handling systems: for example actuated by means of an hydraulic cylinder.
The handling systems with flexible elements, and more precisely the feeling systems with ropes consist in the application on the machine of one or more winches comprising a drum around which a rope is wound. The tractions can be “multiplied” with returns where the introduction/extraction force is increased, to the detriment of handling speed of the digging means: the greater the handling force, the lower the force which can be applied over them. To each doubling of a traction corresponds half sliding speed of the power assembly along the tower.
In drilling machines of the last generation, a nominal extraction force of the digging means, at 100 t is very common. To obtain such a force, with a winch with a traction capability of 25 t, it is necessary to provide a return in the fourth grade. If the speed of the rope is 80 m/min with a direct traction, this speed will be proportionally reduced at only 20 m/min with a traction of the fourth grade. The multiplied tractions require the mounting of a relevant quantity of pulleys perfectly and mutually aligned, both on the power assembly and its upper end (head) and lower end (foot) of the tower. This fact causes a relevant difficulty in designing the carpentry and a distribution of the weights housed in very high positions, with a consequent arising of the centre of gravity of the machine, damaging its stability and with more difficulties in lifting the tower in case of self-lifting tools. The presence of a plurality of pulleys causes a loss of efficiency and the actual traction becomes greatly lower than the nominal one.
Despite the complexity and the cost of the handling systems with ropes, these permit in general, a more rapid conversion of the machine from one technology to the other (for example passing from a machine configuration for providing drilled poles to a configuration for providing constipated poles) with respect to the handling systems of the rigid type, such as the cylinder type.
The handling systems with flexible elements, provided with a motor-reducer and a chain are completely equal to the previous ones, but owing to their dimensioning and the required weights, they are installed in few cases in which relevant extraction/pushing forces combined with limited strokes are required. Practically in the smaller-size machines it is possible to obtain more frequently this type of solution instead of the handling system with winches and ropes.
The handling systems of the cylinder type are cheaper and lighter for being applied on the towers and they have very high yields, but they permit limited strokes, normally not higher than 10 m with pushing forces around 30 t. The translation speed of the cylinders depends on the flow and on the diameters, but it can be approx. 10-15 m/min.
Practically, the handling system of the cylinder type, despite its simplicity, provides strokes and extraction speeds lower than the system of the rope type.
Also, the machine conversion needed to pass from one technology to the other requires long transformation times, especially if it is performed in a yard.
EP 1,672,165 illustrates a handling system of a digging assembly operating by means of chains, fixed to a guide tower, on which pinions connected with motor-reducers engage, whose casing is linked to the structure itself of the power assembly. By imposing a rotary motion to the pinion by means of motor-reducers, one can obtain the handling and so pulling and the pushing on the power assembly. The system, despite the fact that it permits to obtain relevant speeds (maximum values around 35 m/min) is limited to traction or pushing forces slightly greater than 10 t, which are not sufficient to satisfy all the digging technologies.